1. Field of the Invention
The present invention relates to an infrared laser energy generating transversely excited atmospheric (TEA) laser generating apparatus incorporating a low pressure gain cell and tuning means to tune and filter the laser energy output thereby eliminating gain-spiking and mode-beating.
2. Description of the Prior Art
A transversely excited atmospheric (TEA) laser energy generating apparatus can be described as an enclosed chamber or envelope containing a gaseous predetermined mixture exposed to an electrical discharge creating laser energy. The laser energy is reflected between a multiplicity of reflective means converting the energy into a laser beam.
The U.S. Pat. No. 4,127,826 dated Nov. 28, 1978 to Charles M. Cason III teaches a laser system utilzing a helium neon laser for transmitting a beam through a dichroic lens into an unstable resonator. A second laser, a carbon dioxide laser, has a beam transmitted through the dichroic to follow the helium neon beam into the unstable resonator whereby the resonator secondary and primary mirrors are adjusted into a parallel orientation. The gain-spike is therefore suppressed eliminating air breakdown.
U.S. Pat. No. 4,352,562 dated Oct. 5, 1982 entitled "Passive Ring Laser Rate of Turn Device with Acousto-Optic Modulation" teaches a ring resonator wherein the frequency of the laser beam is altered by passing the beam through an acousto-optic filter. The acousto-optic modulation is capable of modulating the laser at frequencies well up into the radio frequency range as is required for cavity stabilization.
U.S. Pat. No. 4,361,889 dated Nov. 30, 1982 utilizes the ring configuration of an array of four reflectors for a narrow line carbon dioxide pump laser wherein the spherical and planar wavefronts are separated from each other along separte opitcal paths and only the planar wavefront is impinged on a plane grating for fine tuning. This plane grating on the output axis is oriented to reflect a portion of the output beam off axis onto a planar relay mirror spaced apart from the output axis in proximity to the concave mirror. The relay mirror reflects plane waves from the grating to impinge on a convex expanding mirror spaced apart from the output axis in the proximity of this grating. Tuning is provided for by rotating the plane grating about an axis normal to the output axis.